Step 1: Understand the grid
A Sudoku board is 9 cells wide and 9 cells tall — 81 cells in total — split into nine smaller 3×3 boxes. Some cells already have a number in them (these are the "givens" and can't be changed); the rest are empty and waiting to be filled in.
Step 2: Learn the one rule
Every row, every column, and every 3×3 box must end up containing the numbers 1 to 9, each exactly once. A number can never repeat within the same row, the same column, or the same box.
Step 3: Select a cell and place a number
Tap an empty cell to select it, then tap a number on the number pad. Sudoku SB will highlight that cell's row, column and box so you can see immediately whether the number fits. If it's correct, it stays; if it's wrong, you'll see clear feedback and lose one of your 3 chances.
Step 4: Use Notes for trickier cells
If more than one number still seems possible in a cell, tap Notes and jot down the candidates in small pencil marks. As you fill in more of the board, you can narrow those candidates down until only one is left.
Step 5: Ask for a hint when you need one
Tap Hint to reveal a helpful number when you're stuck. You get a limited number of hints per puzzle, but there's no penalty for needing them — they're there to keep the game enjoyable, not to be avoided.
Step 6: Finish the puzzle
Once every cell is correctly filled in, the puzzle is solved — Sudoku SB shows your time, score, mistakes and hints used, and lets you share the result or jump straight into another puzzle.